Thomas Malina

Atlas-based segmentation of bone structures to support the virtual planning of hip operations

Two 3-D digitised atlases of a female and a male pelvis were generated to support the virtual 3-D planning of hip operations. The anatomical atlases were designed to replace the interactive, time-consuming pre-processing steps for the virtual operation planning. Each atlas consists of a labelled reference CT data set and a set of anatomical point landmarks. The paper presents methods for the automatic transfer of these anatomical labels to an individual patient data set. The labelled patient data are used to generate 3-D models of the patients bone structures. Besides the anatomical labelling, the determination of measures, like angles, distances or sizes of contact areas, is important for the planning of hip operations. Thus, algorithms for the automatic computation of orthopaedic parameters were implemented. A first evaluation of the presented atlas-based segmentation method shows a correct labelling of 98.5% of the bony voxels.

Realtime bioelectrical data acquisition and processing from 128 channels utilizing the wavelet-transformation

Abstract We propose a versatile signal processing and analysis framework for bioelectrical data, and in particular for neural recordings and EEG. Within this framework the signal is decomposed into subbands using fast wavelet transform algorithms, executed in real-time on a current digital signal processor hardware platform. The decomposition is used to perform various processing and analysis tasks. Besides fast implementation of high, band, and low pass filters, the decomposition is used for denoising and lossy, as well as lossless compression. Furthermore specific electrophysiologic analysis tasks like spike detection and sorting are performed within this decomposition scheme.

Test of spike-sorting algorithms on the basis of simulated network data

Results of spike-sorting algorithms are usually compared with recorded signals which themselves underly interpretations, distortions and errors. Our approach is to provide and compare physiological extracellular potential data by a realistic cortical network simulation. For this purpose, we utilize the neural simulator GENESIS and simulate a region of rat hippocampus containing 90 cells. We are able to “record” simulated extracellular potentials from “virtual electrodes” and produce test data closely resembling multisite neuronal recordings. Our realisitic, arti8cial data are complex and almost natural in appearance; however, current spike detection schemes appear unable to reliably detect all spikes produced. c � 2002 Elsevier Science B.V. All rights reserved.

Atlas-Based Recognition of Anatomical Structures and Landmarks to Support the Virtual Three-Dimensional Planning of Hip Operations

This paper describes methods for the atlas-based segmentation of bone structures of the hip, the automatic detection of anatomical point landmarks and the computation of orthopedic parameters. An anatomical atlas was designed to replace interactive, time-consuming pre-processing steps needed for the virtual planning of hip operations. Furthermore, a non-linear gray value registration of CT data is used to recognize different bone structures of the hip. A surface based registration algorithm enables the robust and precise detection of anatomical point landmarks. Furthermore the determination of quantitative parameters, like angles, distances or sizes of contact areas, is important for the planning of hip operations. Based on segmented bone structures and detected landmarks algorithms for the automatic computation of orthopedic parameters were implemented. A first evaluation of the presented methods will be given at the end of the paper.

TOWARDS A VERSATILE SYSTEM FOR ADVANCED NEURONAL RECORDINGS USING SILICON MULTISITE MICROELECTRODES.

1 Med. Universitat zu Lubeck, Institut fur Signalverarbeitung und Prozesrechentechnik, Seelandstr. 1a), 23569 Lubeck, Germany. * corresponding author 2 ACREO AB, 16440 Stockholm-Kista, Sweden 3 Uwe Thomas RECORDING, Giessen, Germany 4 Universitaire Instelling Antwerpen, Laboratory for Theoretical Neurobiology, 2610 Antwerp, Belgium 5 Istituto Nazionale Neurologico Carlo Besta, Neurofisiologia Sperimentale, 20133 Milano, Italy 6 Aalborg Universitet, Center for Sensory-Motor interaction, 9220 Aalborg, Denmark

Automatische Berechnung orthopädischer Maßzahlen auf der Basis virtueller dreidimensionaler Modelle der Hüfte

Orthopadische Maszahlen, wie Winkel, Abstande etc., bilden eine wesentliche Grundlage fur die orthopadische Diagnose und Therapieplanung. Konventionell werden diese Mase anhand von Rontgenprojektionsbildern gewonnen. Das hier vorgestellte Programm OrthoCalc berechnet orthopadische Maszahlen anhand virtueller dreidimensionaler Modelle der beteiligten Knochenstrukturen und assoziierter Landmarken. Es werden Algorithmen prasentiert, welche die automatische Bestimmung eines patientenbezogenes Koordinatensystem, der Rotationszentren und der Kontaktflache des Huftgelenks und verschiedener orthopadisch relevanter Winkel des Beckens ermoglichen. Durch eine integrierte Visualisierungskomponente kann der Arzt die berechneten Werte validieren. Die Benutzung dreidimensionaler Modelle fur die Berechnung der orthopadischen Kenngrosen erlaubt die korrekte Erfassung der dreidimensionalen Lagebeziehungen und vermeidet auf Projektionsfehlern beruhende Ungenauigkeiten. Durch die automatisierte Berechnung der Maszahlen wird der Arzt von dem damit verbundenen komplexen Interaktionsaufgaben in der virtuellen Umgebung entlastet.

AN INTEGRATED SYSTEM TO TRIGGER FEEDBACK-COUPLED EVENT RELATED BRAIN POTENTIALS

INTRODUCTION Long going physiological research [1], strongly suggests that the macroscopic electric (i.e. EEG) state of a subjects brain influences the responses to defined stimuli, manifested in evoked (or event-related) potentials. Since this evidence is up till now based on post-hoc evaluation of EEG data, we designed and built a data acquisition system able to fully digitally record raw EEG signals from up to 32 scalp electrodes in standard configuration over a prolonged period of time. The design was furthermore meant to evaluate the incoming signals according to user defined criteria and in succession trigger the stimulus to evoke an ERP by either of auditory, visual or sensory stimuli [4]. All these requirements have to be satisfied within the space and financial constraints given by off-the-shelve PC technology.

Ein anatomischer Atlas zur Unterstützung der virtuellen Planung von Hüftoperationen

Aus den hochaufgelosten CT-Volumen einer Frau und eines Mannes wurde ein anatomischer Atlas zur Unterstutzung der virtuellen Planung von Huftoperationen generiert. In den Datensatzen wurden die verschiedenen Knochenstrukturen markiert und die Positionen anatomischer Punktlandmarken festgelegt. Die Werkzeuge DemonReg und OrthoCalc bieten die Moglichkeit, Atlasinformationen automatisch auf Patientendaten zu ubertragen und orthopadische Kenngroβien zu berechnen.